The present invention relates to a sensor element, in particular for determining an angle of rotation, having a detection medium whose position varies as a function of a change in a parameter to be measured, where the change in the position of the detection medium leads to a change in an analyzable signal of the sensor element which is influenced by the detection medium.
A previously proposed sensor element, for example, operates according to a potentiometric or optical principle are known in precision mechanics. Due to a rotational motion of a part having this sensor element, a change in resistance is triggered, leading to a change in an analyzable electric signal, or in the case of sensor elements that function optically, an optical signal is influenced as a function of a rotational position, so that it generates an analyzable signal, e.g., by way of a photoelectric cell. In addition, Hall sensors are also known, which utilize the effect that, in the case of a current-carrying conductor with current flow perpendicular to a homogeneous magnetic field, a voltage difference can be picked up perpendicular to the current flow and perpendicular to the magnetic field. A disadvantage of the previously proposed sensor elements is that they have a relatively complicated design, and consequently only a limited reduction in their size is possible.
The sensor element according the present invention offers the advantage that it has a simple design and can detect a change in the angle of rotation with a high sensitivity. It is possible to achieve transformation of the angle of rotation very advantageously into a force which can be analyzed as the degree of the angle of rotation due to the fact that the detection medium has at least one current-carrying conductor loop which is exposed to an external magnetic field, preferably homogeneous or having a preferred direction, and the detection medium is rotationally movably mounted so that a rotational motion of the detection medium about an angle of rotation in the plane of the magnetic field is converted into a deflection of the detection medium perpendicular to the magnetic field. It is thus easy to perform a non-contact measurement of an angle of rotation. In particular when the sensor element is produced by using surface micromechanics, e.g., on a wafer having an integrated circuit, high-precision sensor elements which are extremely small and lightweight can be manufactured in a manner suitable for mass production. Thus, these sensor elements can also be arranged on sensitive parts where a change in their angle of rotation is to be detected.
This sensor element is suitable not only for detecting a change in the angle of rotation but also for detecting an angle of rotation which may remain unchanged for a very long period of time.
In a preferred embodiment of the present invention, the sensor element has two detection media arranged so they are rotated 90xc2x0 relative to one another. This permits complete detection of the angle of rotation over 360xc2x0 in a very advantageous manner. At the same time, overtwisting, i.e., repeatedly rotating a full 360xc2x0 C., is also possible without the sensor striking a mechanical stop or the like.
In a further preferred embodiment of the present invention, the detection medium is a torsion structure which can be twisted about a fixed axis. An external angle of rotation or a change in an external angle of rotation can thus be transformed into an internal torsion angle or a change in an internal torsion angle. The internal torsion angle or the change in internal torsion angle can preferably be detected by a differential capacitance measurement based on the fact that a change in a torsion angle leads to a change in an electric signal influenced by a capacitance.